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The performance of wood preservatives in soil-bed soft rot tests
1993 - IRG/WP 93-20007
Testing the efficacy of wood preservatives in soil is recognised as a fundamental part of the assessment of long-term wood protection in ground contact. Laboratory based tests can provide a hazardous environment in which a preservative can be challenged by a range of micro-organisms. This paper presents the results of tests carried out to investigate the performance of wood preservatives in a wet soil environment using both strength loss and weight loss as the main criteria for performance assessment.
G R Williams, S Caswell


L-joint trials: Part 3: Relative performance of a range of preservative products
2002 - IRG/WP 02-30292
Long-term trials using the L-joints described in BS EN 330 and AWPA Standard E9-97 have been in progress at BRE since 1982. This paper records the current assessments of decay of L-joints in trials started between 1982 and 1994 with treatments applied to both Scots pine sapwood (Pinus sylvestris) and spruce (Picea sp.). Data are provided on a range of active ingredients including TnBTO, PCP, acypetacs zinc, azoles, isothiazolones, IPBC and disodium octaborate tetrahydrate.
J K Carey


Amine Oxides for Use in Wood Protection: I. A Formulation Adjuvant and Performance Enhancer for Wood
2007 - IRG/WP 07-30425
Amine oxides have great potential for use in the area of wood protection. This paper highlights the advantages of using amine oxides as a formulation adjuvant and performance enhancer for different azoles. It was found that azoles are readily soluble in aqueous amine oxide solutions and form soluble concentrates. These azole/amine oxide concentrates have excellent storage stability and can be diluted with water to obtain clear solutions for end use applications. The mold resistance of the azole treated wood was considerably improved with the addition of amine oxides. Two-year above ground tests revealed that the combination of amine oxides and azoles significantly improved efficacy against molds compared to amine oxides or azoles alone. The lap joint test showed no decay or only slight degradation at all retention levels after five years, while the untreated controls had severe decay with numerous failures.
Xiao Jiang, L Walker


Amine Oxides for Use in Wood Protection: III. Penetration Aids for Wood
2008 - IRG/WP 08-30461
This paper highlights the advantages of using amine oxides as penetration aids for quaternary ammonium compounds (quats) and azoles in the area of wood protection. It was found that the use of amine oxide effectively enhanced the penetration and distribution of quats and azoles. For both southern yellow pine (SYP) and Douglas fir wood samples, the addition of cocodimethylamine oxide (Barlox® 12) in didecyldimethylammonium bicarbonate/carbonate (Carboquat® 250T) significantly improved the penetration of Carboquat® 250T. SYP and Douglas fir wood blocks treated with Barlox® 12 and Carboquat® 250T exhibited 60% and 57% increase respectively in quat retention in the center cross section wafer compared to samples treated with Carboquat® 250T alone. The blend of Barlox® 12 and propiconazole treatment showed roughly a 37% and 33% improvement in azole retention in the middle cross section piece of SYP and Douglas fir wood blocks. Using amine oxide, the retention of quat and azole in the inner zone was comparable to the retention of quat and azole in the outer zone in the absence of amine oxide. The color indicator spray test and chemical analysis illustrated an even distribution of the active preservatives of quat and azole in wood with the aid of amine oxide. It was further confirmed by chemical analysis that amine oxide can carry quats and azoles into wood to the same depth as amine oxide travels into the wood. Therefore, it is suggested that amine oxide measurement can be used as a surrogate agent to determine the presence of azoles in the treated wood.
Xiao Jiang


Near infrared spectroscopy for the quantification of wood preservatives
2008 - IRG/WP 08-20391
Near infrared (NIR) spectroscopy is a rapid, flexible, inexpensive and non-destructive technology that has many applications, including the evaluation of many wood properties. Initial studies have indicated the potential to apply NIRS for the quantification of wood preservatives. However, further evaluation with borate and azole preservative systems has revealed that NIRS technology is challenged by the variability of wood and low preservative retentions. Quantification of certain wood preservatives for quality control purposes using NIRS does not appear to be practical at present.
A M Taylor, Seung H Baek, Myong K Jeong, J D Lloyd, J J Morrell


Accelerated H3 above-ground decay trials in Australia
2009 - IRG/WP 09-20411
An above-ground H3 fungal field trial was installed at five sites (3 in Australia, 2 in New Zealand), with the aim of finding a method that would shorten the time required for evaluating new preservatives and protection systems. One-quarter of the H3 preservative retentions were mostly installed, as first results suitable for registration occur when these reach 70% soundness. Chemical analysis of spare treated specimens gave retentions that averaged 9% lower than determined by solution uptake. This paper provides the exposure results from Australia after one year. At Clayton near Melbourne, untreated Pinus radiata test specimens had highest moisture content in the ‘rot box’ design, followed by the ground proximity and ‘embedded test’, while ‘flat panels’ were driest. Most extensive decay occurred in tests where wood separators between test specimens had been pre-inoculated with Gloeophyllum abietinum (brown rot) or Perenniporia tephropora (white rot). At Innisfail in frames not intentionally pre-inoculated, water-treated P. radiata was extensively decayed when ‘flat panels’ were placed on an aged test frame. Minor decay to water-treated P. radiata occurred in the ground proximity, deck-on-ground and rot box tests. In comparison, no decay was found in the embedded, flat panel (new frame), raised deck, modified double layer and peg tests. The treatments under test included CCA, copper chromate, alkaline copper high quat (AChQ), copper azole, azoles, kerosene, boron, TBTN, and copper naphthenate. Untreated Corymbia maculata heartwood was included as an example for natural durability.
L J Cookson, J Carr


Accelerated H3 above-ground decay testing
2013 - IRG/WP 13-20520
An above-ground H3 fungal field trial was installed at two sites in Australia and one in New Zealand, as well as in two Accelerated Field Simulators. The aim was to find a method that would shorten the time required for evaluating new preservatives and protection systems. One-quarter H3 retentions were installed, as first results suitable for registration occur when these reach 70% soundness. Twelve test methods were examined, some established and others developed for the project. In two methods, feeder blocks pre-inoculated with laboratory-raised fungi were placed next to test specimens in an effort to accelerate decay. The treatments examined were CCA, alkaline copper high quat (AChQ), azoles, kerosene, TBTN, and water. Untreated Corymbia maculata heartwood was included for natural durability. Inspection was annual for four years. The fastest test was the ‘rot box’ at Innisfail, followed by the ground proximity, deck-on-ground and embedded tests. The most reliable tests giving expected relative order of failure were those allowing diversity of fungi rather than those that became dominated by a few, and included those placed close-to-ground or those with increased volume of untreated wood substrate in frames. Pre-inoculation with Gloeophyllum abietinum gave more representative results than those pre-inoculated with Oligoporus placenta.
L J Cookson, D Page, T Singh


Buffered Amine Oxide Treatment Systems for Imparting Water Based Azoles/Insecticides in Douglas Fir and Eucalyptus
2015 - IRG/WP 15-40707
In today’s world, wood remains the most versatile, practical and sustainable building material. In contemporary countries, wood is a well-managed renewable resource that has a remarkably small carbon footprint compared to those of steel, aluminium, composites, and concrete. These alternative materials have continued to emerge as viable building materials given the durability issues of untreated wood against attack from insects and fungi. As these materials continue to take market share away from wood, the need to cost-effectively increase the durability of wood remains an always present target within the forest products industry. The use of chemical treatments to impart fungal and insect resistance into wood has been utilized for over a century. Today, many of these preservatives are delivered into the wood using the same decades-old methods and chemicals, including the utilization of emission-prohibitive organic solvent based delivery systems. The development of solvent-free, Water Based Buffered Amine Oxide Treatment Systems (known commercially as TRU-CORE® Technology) for use in wood preservation has allowed significant modernization of the application and preservation process. The buffered amine oxides allow for a chemically based infusion process that is capable of delivering key wood protectants completely throughout the wood. This waterbased system imparts a minimal amount of added moisture into the wood during the process, so there is no need to dry after treatment. A short activation period is utilized to achieve full penetration. For larger wood profiles, such as decking members and railroad crossties, the use of pressure/vacuum impregnation accelerates the penetration. The Buffered Amine Oxide Treatment System is in commercial use in the United States, New Zealand and Australia; where numerous programs have been developed for residential and industrial wood products. To date, over 2,000,000 m3 (847,552,001 board feet) of wood has been treated utilizing the Buffered Amine Oxide Treatment System. The most modern Buffered Amine Oxide Treatment System has been designed to fully and completely impart azoles/insecticide wood preservatives into Douglas Fir and Eucalypt wood profiles.
R W Clawson Jr


A Treatability Study of Western Wood Species with Water Based Azoles and Insecticides Using Buffered Amine Oxides
2016 - IRG/WP 16-40766
The use of Western U.S. Wood Species remains small in today’s global wood product market when compared to the use of other commercially available softwoods. One reason that other fiber sources, those that may be less naturally durable or exhibit slightly inferior mechanical properties, are utilized is ease of treatment. In an attempt to ensure adequate penetration in commercially important and difficult-to-treat Western Wood Species such as Douglas fir, Hem fir, and 100% Heart Redwood, the use of deep incisions is standard practice. The development of solvent-free, Water Based Buffered Amine Oxide Treatment Systems (known commercially as TRU-CORE® Technology) for use in wood preservation has allowed significant modernization of the application and preservation process for these species. Important to the future growth of Western Wood Species may be the elimination of incising. When the Buffered Amine Oxide Treatment System technology is utilized it has been demonstrated that non-incised difficult-to-treat species are fully penetrated in the sapwood and heartwood. The buffered amine oxides allow for a chemically based infusion process that is capable of delivering key wood protectants completely throughout the wood. This water based system imparts a minimal amount of added moisture into the wood during the process, so there is no need to dry after treatment. To date, there are over 50 commercially successful Buffered Amine Oxide Treatment Systems. In 2015, over 4,000,000 m3 (1.695 billion board feet) of wood was treated with the Buffered Amine Oxide System.
R W Clawson Jr, C N Cheeks, K A Cutler